It is known to use pumps to provide drilling mud under pressure in the drilling of wells. Pressurized drilling mud is delivered down a hollow drill string as the well is being drilled to carry away cuttings up the annulus surrounding the drill string to ground level. Such drilling operations are well known to those skilled in the art.
Prior art pumps can use a motor to turn a crankshaft or “pump shaft” to convert rotary motion to a reciprocating motion. The pump shaft moves a connecting rod coupled to a crosshead that moves within a fixed crosshead slide to provide this conversion. The crosshead is coupled to a “pony rod” that, in turn, is coupled to a piston rod that provides the pumping motion in a pump module, as well known to those skilled in the art.
The above-mentioned mechanical arrangement can be multiplied so that a multitude or plurality of pump modules can be operated from a single pump shaft. The outputs of each pump module can be coupled to a common manifold from which pressurized drilling mud can be provided to the drill string. By coupling the pump module outputs to a common manifold, the pulsing of the pressure of the drilling mud can be reduced or smoothed out, this being a problem well known to those skilled in the art. The disadvantage of this mechanical arrangement is the size and complexity of the components involved to provide a multi-module pump.
It is also known in the oil and gas industry to drill horizontal wells. These are wells that are initially drilled vertically and, with the use of directional drilling equipment as well known to those skilled in the art, the direction of drilled well becomes horizontal or parallel with the ground surface. It is known to drill horizontal wells 5000 to 7500 feet in length or more. To do so requires the use of “mud motors”, motors that are powered by the delivery of highly pressurized drilling mud pumped through the drill string so as to enable the turning of the drill bit. It is also known that to drill such wells, drilling operators will use at least two or more conventional mud pumps powered by 1000 horsepower or more motors. Each mud pump is housed in its own pump house and occupies space at the drilling site. As each additional pump house increases the number of structures at a drilling site, the number of truckloads required to deliver the necessary equipment to a drilling site also increases. All this additional equipment and number of truckloads to deliver the equipment add cost to the drilling of the well.
It is, therefore, desirable to provide a pump that can convert rotary motion to reciprocating motion without having to use connecting rods, crossheads, crosshead slides and pony rods to reduce its size, complexity and cost to manufacture. It is also desirable to provide a mud pump that is compact in size but can deliver pressurized mud at a volume equivalent to two or more conventional mud pumps.